Novel PLA/Chitosan Composite Materials Prepared by SCF-CO2 Technique

Because of the incomparable merits （nontoxicity, non-remainder, fast transfer mass） of supercritical carbon dioxide fluid technique（SC-CO2）, it was used to developed a series of novel biodegradable tissue engineering scaffold materials in this research. The novel PLA/chitosan composite materials could be molded to different shapes, and the porosity of the materials were over 200 lam and connected. Chondrocyte cultivation, subcutaneous and intramuscular implantation were mainly discussed this paper. The results showed that the cells could well adhere, grow and multiplicate on the surface of the materials, which indicated good biocompatibility of the composite materials. The plantation test revealed that the PLA materials had already dismissed 2 month late in the body, while the composite materials could still keep certain strength and shape, and the most important things is the response of the tissue toward the implanted PLA/chitosan composite materials was mild and had far less inflammation than PLA materials. 8 to 16 weeks later, fiber membrane was stable; degradation of the materials was seen clear and tissue had already spread into it.     

Quantification of the repair process involved in the repair of a cell monolayer using an in vitro model of mechanical injury

The processes of wound repair were investigated using an in vitro model of mechanical injury on confluent cell monolayers of either human umbilical vein endothelial cells (HUVEC), aortic endothelial (RAEC) or smooth muscle cells (VSMC) of the rat. A mechanical wounder was used to produce 11 parallel (400m wide) lesions across the monolayer and the movement of cells into the denuded area was quantified using image analysis. The lesioned area recovered completely in 72h, with proliferation occurring after 24h for endothelial cells and 18h for VSMC, as detected by an increase in cell numbers. The cell migration inhibitor Taxol® (1ng/ml) abolished the increase in repair of HUVEC monolayers in the first 24h of repair, while actinomycin D had no effect before 24h but thereafter abolished the further repair which was associated with increased cell numbers. Repair of endothelial cells was accelerated by basic fibroblast growth factor (bFGF), vascular endothelial growth factor or platelet-derived growth factor-BB (PDGF), and in VSMC both bFGF and PDGF increased repair. This simple in vitro model of mechanical injury allows a quantitative study of the repair processes of a previously confluent monolayer and thus is a representation of mechanical damage in vivo. [© 1998 Rapid Science Ltd.]     

Analyses of phenotype and genotype in acute lymphoblastic leukemias at first presentation and in relapse

As a clue to the cellular origin of leukemic populations in relapse we analyzed 11 cases of acute lymphoblastic leukemia (ALL) by immunological and molecular genetic approaches. Blast cells obtained from both initial diagnosis and relapse were immunophenotyped using a variety of monoclonal antibodies; simultaneously we hybridized Southern blots of respective cell samples to immunoglobulin (Ig) heavy and light chain as well as to T-cell receptor beta-chain (T beta) sequences. While similar phenotypes were observed in both states of nine cases, comparison of Ig gene rearrangements revealed clonal variations, ie, appearance of an evoluted or novel leukemic cell clone in relapse beside identical leukemic populations in both states. One pre-T (ALL) patient, presenting with germline configuration of T beta gene sequences at diagnosis, exhibited a rearrangement of T beta gene sequences in recurrent disease. Another patient displayed T-ALL phenotype and T beta gene rearrangement at diagnosis but relapsed with a very immature phenotype and germline configuration for T beta sequences. Our results emphasize the value of molecular analyses in order to unravel the nature of leukemic relapse.     

T lymphocytes lack rearrangement of the bcr gene in Philadelphia chromosome-positive chronic myelocytic leukemia

To study the possible involvement of T lymphocytes in Philadelphia chromosome (Ph)-positive chronic myelocytic leukemia (CML) we analyzed the arrangement of the bcr gene in T cell and non-T cell samples of 12 CML patients. Although all the patients showed bcr rearrangements in non-T cell fractions, T cell populations lacked respective gene recombinations. Moreover, by Southern blot analyses using T cell receptor beta chain sequences our data indicate polyclonality of T cell samples from 11 of 12 cases; in one patient a clonal T cell population could be identified. These results suggest that T lineages of most Ph- positive CML patients are not derived from pluripotent stem cells involved in leukemogenesis and thus confirm previous investigations based on cytogenetic or glucose-6-phosphate dehydrogenase analyses. The demonstration of polyclonal T cell populations may reflect persistence of stem cells committed to differentiate only into T cells.     

Clonal hematopoiesis as defined by polymorphic X-linked loci occurs infrequently in aplastic anemia

We evaluated the methylation status of the X-linked gene phosphoglycerate kinase (PGK1) and the DXS 255 locus detected by probe M27 beta to study clonality in acquired aplastic anemia (AA). A total of 30 females were suitable for clonal analysis of peripheral blood polymorphonuclear cells (PMN) and mononuclear cells using a polymerase chain reaction-based procedure in 24 patients and Southern blotting in 9. Overall, 10 of 30 patients exhibited an imbalanced X-inactivation pattern. However, in 4 patients, analysis of constitutional DNA suggested a skewed methylation pattern and 2 further cases had to be excluded because of the lack of an appropriate control. A truly clonal pattern was thus established in 4 of 30 (13%) patients. In 7 patients who later developed clonal disorders of hematopoiesis, X-inactivation analysis did not predict this event in any case. In patients with a paroxysmal nocturnal hemoglobinuria phenotype, there was no correlation between the proportion of phosphatidylinositol glycan anchored protein (PIG-AP)-deficient blood cells and the corresponding X-inactivation pattern. X-inactivation analysis detected clonal hematopoiesis in only 3 of 10 patients with a deficiency in PIG-AP in the cell population under study, but sorting of nucleated cells on the basis of PIG-AP expression showed the clonal nature of PIG-AP-deficient cells. We conclude that the majority of patients with AA show polyclonal hematopoiesis using X-linked clonal analysis, but that minor clonal populations, such as PIG-AP-deficient cells, may not be detected unless sorted cell populations are separately analyzed.     

Evidence that SE is distal to LU on chromosome 19q

Analysis of a family informative for chromosome 19 loci establishes that the Lutheran blood group locus (LU) lies between the third component of human complement (C3) and the secretor loci (SE). Previously published lod scores for C3:LU are increased from 2.94 to 3.80. The linkage relationships (zeta and theta) between C3, LU, and SE are examined, and the proposed order and approximate genetic distances are determined to be: pter--C3-10.6cM-cen-7.4cM-LU-9cM-SE--qter.     

Emergence of B-immunoblastic sarcoma in patients with multiple myeloma: a clinicopathologic study of 10 cases

Immunologic and histologic studies were performed in 10 cases of myeloma that showed progression to a more aggressive proliferation, designated as immunoblastic sarcoma of B-cell type (B-IBS). Several patterns of clinical presentation were observed: eight patients showed typical multiple myeloma, four developed B-IBS within the bone marrow, and four developed B-IBS in multiple extramedullary sites; the remaining two patients had relatively localized myeloma, but also showed development of extramedullary B-IBS. The implications of these findings are discussed with regard to their prognostic import and their relationship to current concepts of plasma cell development.     

Spontaneous Epstein-Barr virus transformed B-cell line sharing the identical immunoglobulin gene rearrangement with acute myeloid leukemia

Mononuclear cells from a 44-year-old patient with acute myeloid leukemia (AML) gave rise to a spontaneous permanent cell line cultured in suspension. The cell line was shown to be positive for Epstein-Barr virus nuclear antigen (EBNA). As expected, its composite phenotype was of B-cell type with B-cell antigens (CD 20, CD 21) and with monoclonal surface IgM of kappa type, but without detectable IgM secretion. Surprisingly, identical monoclonal rearrangements of the immunoglobulin heavy chain (JH) sequences could be demonstrated in the uncultured bone marrow AML cells and in the cell line that also had kappa light chain gene rearrangement. This is the first case to our knowledge of an EBNA positive B-cell line with identical monoclonal Ig heavy chain rearrangement as detected in myeloblastic leukemia cells.